Monaural in-the-ear earphones for listening to AM/FM transistor radios have been used for decades but it was arguably not until the introduction of the WALKMAN® portable stereo music player by Sony Corporation in 1979, that portable devices for playing audio and audio/video material began to assume the widespread popularity among consumers. The form and format of these devices as well as the storage media for the material they play, are diverse and have evolved rapidly. Portable transistor radio broadcast receivers were eclipsed by magnetic tape cassette players which gave way to portable optical Compact Disc Players which were followed by the emergence of Digital Video Disc players and so-on. At the present time, portable stereo audio devices are available which are very lightweight and compact. They are capable of selectively accessing and storing vast amounts of program material directly from the Internet encoded according to any of a variety of protocols. MP3 players are now tremendously popular, perhaps none more so than the Apple® Ipod® and others now being marketed by Microsoft Corporation and a host of companies. Despite the pace of technological development in the field, a characteristic which all such devices have shared, and are likely to continue to share for the foreseeable future, is that they rely on miniature stereo audio earphones to carry audio electrical signals from the device and convert them into sound which can be enjoyed by the listener without disturbing others nearby and do so in a form factor minimizes size and maximizes portability.
In a popular type of miniature stereo audio earphones, each of a pair of earphones has an outer housing containing a miniature audio transducer which converts electrical signals of one stereo channel into sound. The housing is shaped and dimensioned to mount comfortably in the ear either just outside, or partially within, the outer ear canal. A generally Y-shaped electronic lead assembly carries audio signals from the audio source to the transducers. Each earphone is mounted at the end of one of a pair of thin, and very flexible wires which make up the bifurcated upper portion of the lead assembly. Each of those thin wires contains electrical conductors for carrying either the right or left channel signal to the corresponding earphone. The two individual wires converge to form a somewhat thicker unitary cable which encases all of the electrical conductors for both channels and terminates in a detachable electrical connector, typically a stereo male jack plug, for making a detachable stereo physical and electrical detachable connection to the audio source. The electrical conductors used are typically braided, or parallel-oriented, arrays of a relatively few strands of very fine copper wire each of which is sometimes not much larger in diameter than a human hair.
Such earphones are capable of extremely high fidelity sound reproduction and are very small, light and flexible. However, they are not without significant disadvantages. Portability comes at a price. Thin, flexible wires serve the objectives of portability and inconspicuousness very well but they result in a structure which tends to be somewhat fragile and is subject to breakage if not handled delicately. This is particularly true of the leads which attach to the earphones. They can be abraded, cut, crushed or kinked rather easily, causing breakage of some of all of the internal conductors. As a result, static or other degradation of audio quality can occur. If one of the conductors breaks completely, the earphones become completely inoperable and must be replaced.
There exists a need for a miniature stereo audio earphone apparatus which is substantially more rugged and resistant to the types of damage just noted, but does not fulfill that objective at the expense of assuming an unattractive appearance.
Existing stereo audio earphones of the type described above are also easily broken or damaged when their lead assembly, especially its thin upper wires, are subjected to even relatively small amount of tension. Leads are inadvertently snagged on objects or otherwise pulled in the course of use or being stored or retrieved from storage. For example, when stored in a pocket or purse, they can easily snag on a set of keys or other objects being carried causing some or all of the electrical conductors in the lead to be pulled apart and/or causing the lead to be pulled out of an earphone.
There also exists a need for a method of making miniature stereo audio earphone products in a manner which provides products having enhanced resistance to damage by providing a bifurcated upper portion thereof with a plurality of mechanical shielding elements which are also capable of providing an improved appearance.